From the Research
Yes, a vitamin B12 (cobalamin) level of 400 pg/mL is a reasonable target and falls well within the normal reference range. The typical normal range for vitamin B12 in adults is approximately 200-900 pg/mL, though exact reference ranges may vary slightly between laboratories. At 400 pg/mL, your level is comfortably above the lower threshold where deficiency symptoms might begin to appear. Vitamin B12 is essential for proper nerve function, DNA synthesis, and red blood cell formation. The body stores vitamin B12 efficiently, primarily in the liver, which can maintain adequate levels for several years even if intake decreases. For most healthy adults, maintaining B12 levels through diet (animal products like meat, fish, dairy, and eggs) or supplements (typically 2.4 mcg daily for adults) is sufficient. However, certain populations may need higher targets or supplementation, including older adults, strict vegetarians/vegans, those with absorption issues (pernicious anemia, certain gastrointestinal conditions), or people taking medications like metformin or proton pump inhibitors.
According to a recent study 1, oral vitamin B12 supplementation can effectively improve vitamin B12 deficiency in patients with pernicious anemia, with significant improvements in plasma vitamin B12, homocysteine, and methylmalonic acid concentrations. This study suggests that oral supplementation with 1000 μg/d of cyanocobalamin can improve vitamin B12 deficiency, which supports the idea that a level of 400 pg/mL is a reasonable target.
Some key points to consider:
- The normal range for vitamin B12 in adults is approximately 200-900 pg/mL 2, 3
- Certain populations may need higher targets or supplementation, including older adults, strict vegetarians/vegans, those with absorption issues, or people taking certain medications 2, 3
- Oral vitamin B12 supplementation can be effective in improving vitamin B12 deficiency, even in patients with pernicious anemia 1
- The body stores vitamin B12 efficiently, primarily in the liver, which can maintain adequate levels for several years even if intake decreases 2, 3
If you're currently supplementing to reach this level, continuing your current regimen would be appropriate, especially if you have a medical condition that requires higher vitamin B12 levels or if you're at risk of deficiency. However, it's always best to consult with a healthcare professional to determine the best course of treatment for your individual needs.